Silicide and Schottky barrier formation in the Ti-Si and the Ti-SiO<i>x</i> -Si systems

Abstract

Silicide and Schottky barrier formation has been characterized for Ti deposited on the Si(100) surface, both with and without surface oxides present. Reactions were carried out in ultrahigh vacuum, while observing electronic and chemical changes with ultraviolet photoemission spectroscopy and Auger electron spectroscopy. Ti deposited on Si shows a sharp interface, no change in Fermi level position, and no silicide formation until heated to 400–500 °C. Ti deposited on thin oxides (&amp;lt;20 Å) frees silicon at the interface and reacts through the oxide to form a silicide when heated to 400–500 °C. Ti deposited on thick thermal oxides also frees Si, but no further reaction occurs until heated to 700–900 °C, at which point TiOx forms near the surface. This differing behavior of thin and thick oxides is shown to be consistent with bulk thermodynamic data.